Dr. Byington is testing the hypothesis that polymerase chain reaction-based rapid diagnostic methods can define the presence or absence of bacterial infections in young infants who present to the emergency room with fevers. The data generated in this protocol, now completed, have indicated that the detection of non-polio enteroviral infections in febrile infants serves as a useful indication that bacterial infection is not likely to be present. Thus, lengthy hospitalizations with expensive antibiotic therapy and invasive diagnostic studies may not be required. The data generated by this study were used in a successful application to the Robert Wood Johnson Foundation to launch an expanded study.